As a crossed roller bearing in which an inner element and an outer element relatively rotate, the following slewing bearing is known: the slewing bearing includes multiple rollers and spacer retainers; the multiple rollers are placed between V-grooves facing each other so that the inclination directions in which adjacent rollers (rolling elements) are each inclined are alternately perpendicular to each other and so that the projected center lines of the rollers is directed towards the centers of inner and outer rings, the projected center lines being obtained by projecting the straight lines aligned with the axes of the rollers respectively onto the plane of rotation of inner and outer rings; and spacer retainers are placed between adjacent rollers in order to prevent skewing (shifting in a certain direction) of the rollers, each of the spacer retainers having concave grooves which the adjacent rollers rotatably fit. In the concave grooves, tilted contact surfaces are provided respectively for each of the rollers, each of the tilted contact surfaces having a vertex at the center in its longitudinal direction and tilts at half the angle between the projected center lines of the adjacent rollers (i.e., [PTL 1]).